525 
Admitting this, I am still of the opinion that the estivo-autumnal is the 
prevailing type of malarial infection in the Philippine Islands. 
In this connection, it should be remembered that the hyaline forms of 
the estivo-autumnal plasmodia are the most difficult of any to demon- 
strate and therefore they are undoubtedly often overlooked, even by 
trained observers. Furthermore, it frequently requires repeated examina- 
tion of the blood and a long and patient search to find them. It is 
perfectly evident when the data are carefully studied, that many, if not 
the majority of the so-called “simple continued fevers” which some 
medical men believe to be so prevalent in these Islands, are really unrec- 
ognized cases of estivo-autumnal malarial infection. 
2. Initial attacks of the malarial fevers are most common among the 
Americans, including in this term all whites. This would be expected, 
and it.is not because of a relative immunity of the natives, for, as will 
be shown, such a relative immunity does not exist. It is due to the fact 
that a very large proportion of the natives in this locality are continually 
infected and suffer from relapses at longer or shorter intervals. It was 
but rarely that I was able to study an initial attack of malaria occurring 
in persons of the latter race and then it was only in very young children 
or in new arrivals. 
3. Latent infections are most common in the natives, none being 
observed in Americans. However, in most of the latent cases a history 
of previous attacks of malaria could be obtained. | 
4. Recurrent attacks among the Americans were comparatively rare, 
due to the fact that every patient infected with malaria when treated 
in the hospital or in the post was required to take quinine once a week 
for several weeks and from our experience with this method there can 
be no doubt of its great efficiency in preventing recurrences of malarial 
infection. 
LATENT INFECTION IN NATIVES OF THE PHILIPPINES. 
The subject of latent infection in malarial disease more and more is 
receiving the attention which it deserves. We now know that an in- 
dividual may harbor the malarial plasmodia for weeks or even months 
without suspecting that he is attacked, and during all of this time he 
may be a source of infection to others. 
The observations of Koch, of Stephens and Cristophers in Africa, 
and of James in India prove that the greatest source of danger to the 
white man in a malarial locality lies in the native population, especially 
in the native children. The control of malarial infection in the Tropics 
will only be possible if quinine is issued to the native, and in the follow- 
ing observations it is my purpose to show that the latter race in the Phil- 
ippines is the source of malarial infection. I will also attempt to show 
the futility of endeavoring to rid any locality of malaria so long as the 
native element in the question is neglected. 
